Until now, we have only had access to 200 years of weather records in South-East Queensland. But our new research used marine sediment cores (dirt from the bottom of the ocean) to reconstruct stream flows and rainfall over past millennia.

This shows that long droughts and regular floods are both prominent features in South-East Queensland’s climate.

This is concerning. Decisions about where we build infrastructure and how we use water have been based on the assumption that our climate – especially rainfall – is relatively stable.

Archives of past climates

Natural archives of climate are preserved within things such as tree rings, coral skeletons, ice cores, lake or marine sediments. Examining them lets us extend our climate records back beyond documented history.

We can then undertake water planning in the context of a longer record of climate, instead of our short-term instrumental records.

In this study, we used sediment cores from Moreton Bay (next to the mouth of the Brisbane River) to reconstruct the river’s flow over the past 1,500 years. In these cores we measured various indicators of fresh water to reconstruct a record of streamflow and regional rainfall.

At the turn of the last millennium the region was in the middle of a prolonged dry spell that lasted some six centuries, from roughly the year 600 to 1200. After about 1350 the region became gradually wetter, with peaks revealing a series of extreme floods in the late 1600s and early 1700s. Large floods in the 1700s have also been documented in the upper reaches of the catchment, in the Lockyer Valley.

These broad shifts in regional rainfall and streamflow are linked to drivers of global climates, including hemispheric cooling and the El Niño-Southern Oscillation.

In addition, the southward displacement of monsoon troughs at this time may have increased the likelihood of cyclone-related weather systems reaching southern Queensland.

This information helps us contextualise the climate of the last 200 years and gives us some insights into how regional rainfall responds to shifts in global climate.

Wet and dry extremes

Over the past 20 years, South-East Queensland has experienced its fair share of extreme weather events. Severe floods have caused deaths and damaged infrastructure. Flooding cost the Australian economy some A$30 billion in 2011.

The millennium drought, which in this region was most severe from 2003-08, resulted in widespread water shortages. This prompted major investment in the South-East Queensland Water Grid, a connected network of dams, water treatment plants, reservoirs, pump stations and pipelines.

So far Queensland has coped with everything Mother Nature has thrown at it. But what if extreme floods and droughts became the norm rather than the exception?

Such events also threaten the ecosystem health of downstream waterways, including the iconic Moreton Bay

Our reconstruction found that big floods over the past 1,500 years rivalled the size of floods in recorded history (1893, 1974 and 2011), but the level of sediment in the water of more recent floods seems to be unprecedented.

This indicates that historical and ongoing land-use changes in the Brisbane River catchment are contributing to more abrupt and erosive floods.

This will continue unless better land management techniques are adopted to improve the resilience of catchments to extreme weather events.

What does this mean for the future?

We are learning that over the last millennium natural climate and rainfall have been more variable than previously thought. This means that modern anthropogenic climate change may be exacerbated by a background of already high natural climate variability.

In addition, our water infrastructure has been built based on a narrow understanding of natural climate variability, limited to the last 200 years. This may mean the quantity of reliable long-term freshwater resources in eastern Australia has been overestimated.

As Australian cities grow and transform, we need to ensure we are not building the slums of the future by making buildings so tall and tight they turn our streets into stark canyons. Sydney’s Wolli Creek, where buildings dominate and tower over a transport hub, is an example of where this is happening. It is now considered one of the city’s densest areas.

Dense, high buildings limit the space available for urban greenery and, unfortunately, the current development boom privileges concrete and glass over vegetation. A more strategic approach to urban growth can ensure our cities maintain adequate green space and become low-carbon, efficient and affordable.

It’s also vital the community and individuals are enthusiastic drivers of such change, with shared ownership of it. Imaginative projects – at times described as urban acupuncture – can all play a role. This is where small-scale interventions (like green balconies) are applied to transform the larger urban context, improve the environment and make the city liveable.

Going up or out

Whether you go up (higher) or out (more), or both, there are always challenges and opportunities.

The drawback in going out is that we start creeping into our remaining open space, including important biodiversity hotspots.

Sydney’s Wolli Creek is considered one of the city’s densest areas.from shutterstock.com

Going out can also encroach on agricultural land. Farmers around the Sydney basin produced up to 20% of the area’s fresh food needs in 2011. But researchers have predicted urban sprawl and rising land prices will lead this to drop to 6% by 2031, losing both produce and jobs.

Going up is an approach driven by proximity to transport, utilities and employment, particularly in Sydney and Melbourne. Major upward developments, like Wolli Creek, are logically being located around transport nodes. But these then become dense and concentrated areas, putting growing pressure on open space and community facilities.

Community projects

Community consultation is key before any major project and redevelopment, as genuine dialogue supports shared ownership of the outcomes. Existing community projects must be celebrated. Having an engaged and empowered community leads to a healthier, happier population.

In Sydney, new precincts like Waterloo are ambitious and have good intentions. These areas aim to deliver new homes, shops, major transport services, community facilities, parks and open spaces over the next 20 years – and they’re located close to the urban centre.

Waterloo already has three community gardens, which bring together public housing residents through growing and sharing fresh produce. This approach is important to continue and initiate new projects.

Green roofs can become community gardens.from shutterstock.com

Around the world there have also been successes with city farming where the community grows and sells agricultural produce locally. In skyscraper Singapore, they are farming vertically at Sky Greens, providing an alternative to importing food for this densely peopled city-state.

Green roofs are another alternative where communities can grow flowers and vegetables while providing training and jobs. A good example is the Uncommon Ground rooftop farm in Chicago.

In Australia, the Grounds is a former pie factory in the industrial heart of Sydney’s Alexandria. In 2012, the site began to metamorphose into a cafe, restaurant, bakery, organic mini-farm and more. This is a successful example of how a little greenery has turned a bleak post-industrial site into an enjoyable destination, where young and old from far and wide come to enjoy the plants, animals and coffee.

The Grounds in Sydney’s Alexandria was transformed from an industrial site into an enjoyable destination.Herry Lawford/Flickr, CC BY

A domestic garden, a green balcony or a green wall can all play a role – but these need ongoing care and attention, which means individuals and engaged communities must drive the enthusiasm.

Nature in the city

So, for a start, let’s not build fast and furiously without grasping the place as a whole and making the most of what is already there. This means preserving mature trees and shrubs, leaving open space unpaved and protecting areas of deep soil for future planting.

Maintaining, enhancing and creating urban green space not only fulfils the requirements for urban acupuncture, but – to mix medical metaphors – provides a kind of urban vaccination against the emergence of slums, where nothing can grow and depression sets in.

As the federal government aims to ink a deal with the states on the National Energy Guarantee in August, it appears still to be negotiating within its own ranks. Federal energy minister Josh Frydenberg has reportedly told his partyroom colleagues that he would welcome a new coal-fired power plant, while his former colleague (and now Queensland Resources Council chief executive) Ian Macfarlane urged the government to consider offering industry incentives for so-called “clean coal”.

Solar PV and wind are now cheaper than new-build coal power plants, even without carbon capture and storage. Unsubsidised contracts for wind projects in Australia have recently been signed for less than A$55 per MWh, and PV electricity is being produced from very large-scale plants at A$30-50 per MWh around the world.

As the graph below shows, medium to large (at least 100 kilowatts) renewable energy projects have been growing strongly in Australia since 2017. Before that, there was a slowdown due to the policy uncertainty around the Renewable Energy Target, but wind and large scale solar are now being installed at record rates and are expected to grow further.

As the graph also shows, this has been accompanied by a rapid increase in employment in the renewables sector, with roughly 4,000 people employed constructing and operating wind and solar farms in 2016-17. In contrast, employment in biomass (largely sugar cane bagasse and ethanol) and hydro generation have been relatively static.

Although employment figures are higher during project construction than operation, high employment numbers will continue as long as the growth of renewable projects continues. As the chart below shows, a total of 6,400MW of new wind and solar projects are set to be completed by 2020.

The Queensland question

Australia’s newest coal-fired power plant was opened at Kogan Creek, Queensland in 2007. Many of the political voices calling for new coal have suggested that this investment should be made in Queensland. But what’s the real picture of energy development in that state?

There has been no new coal for more than a decade, but developers are queuing up to build renewable energy projects. Powerlink, which owns and maintains Queensland’s electricity network, reported in May that it has received 150 applications and enquiries to connect to the grid, totalling 30,000MW of prospective new generation – almost all of it for renewables. Its statement added:

A total of more than A$4.2 billion worth of projects are currently either under construction or financially committed, offering a combined employment injection of more than 3,500 construction jobs across regional Queensland and more than 2,000MW of power.

As the map below shows, 80% of these projects are in areas outside South East Queensland, meaning that the growth in renewable energy is set to offer a significant boost to regional employment.

Tropical North Queensland, in particular, has plenty of sunshine and relatively little seasonal variation in its climate. While not as windy as South Australia, it has the advantage that it is generally windier at night than during the day, meaning that wind and solar energy would complement one another well.

Renewable energy projects that incorporate both solar and wind in the same precinct operate for a greater fraction of the time, thus reducing the relative transmission costs. This is improved still further by adding storage in the form of pumped hydro or batteries – as at the new renewables projects at Kidston and Kennedy.

Remember also that Queensland is linked to the other eastern states via the National Electricity Market (NEM). It makes sense to build wind farms across a range of climate zones from far north Queensland to South Australia because – to put it simply – the wider the coverage, the more likely it is that it will be windy somewhere on the grid at any given time.

This principle is reflected in our work on 100% renewable electricity for Australia. We used five years of climate data to determine the optimal location for wind and solar plants, so as to reliably meet the NEM’s total electricity demand. We found that the most cost-effective solution required building about 10 gigawatts (GW) of new wind and PV in far north Queensland, connected to the south with a high-voltage cable.

Jobs and growth

This kind of investment in northern Queensland has the potential to create thousands of jobs in the coming decades. An SKM report commissioned by the Clean Energy Council estimated that each 100MW of new renewable energy would create 96 direct local jobs, 285 state jobs, and 475 national jobs during the construction phase. During operation those figures would be 9 local jobs, 14 state jobs and 32 national jobs per 100MW of generation.

Spreading 10GW of construction over 20 years at 500MW per year would therefore deliver 480 ongoing local construction jobs and 900 ongoing local operation jobs once all are built, and total national direct employment of 2,400 and 3,200 in construction and operations, respectively.

But the job opportunities would not stop there. New grid infrastructure will also be needed, for transmission line upgrades and investments in storage such as batteries or pumped hydro. The new electricity infrastructure could also tempt energy-hungry industries to head north in search of cheaper operating costs.

One political party with a strong regional focus, Katter’s Australia Party, understands this. Bob Katter’s seat of Kennedy contains two large renewable energy projects. In late 2017, he and the federal shadow infrastructure minister Anthony Albanese took a tour of renewables projects across far north Queensland’s “triangle of power”.

Katter, never one to hold back, asked “how could any government conceive of the stupidity like another baseload coal-fired power station in North Queensland?” Judging by the numbers, it’s a very good question.